The present invention relates to a key switch consisted of a key cap, a key base and a rubber tone in which the key cap has a unitary, hollow, rectangular plunger inserted into a hole on the key base and pressed to squeeze the rubber tone in producing a respective pulse signal.
FIG. 1 illustrates a key switch according to the prior art, which is generally comprised of a key cap (1a), a rectangular plunger (2a), a key base (3a), and a rubber tone (4a). Pressing the key cap (1a) causes the rectangular plunger (2a) to slide downwards in a rectangular hole on the key base (3a), and therefore the rubber tone (4a) is squeezed to drive a conductor to contact a contact on the printed circuit board below. Because the key cap (1a), the rectangular plunger (2a), the key base (3a) and the rubber tone (4a) are separately made, the assembly process of this structure of key switch is complicated, and the total height of this structure of key switch can not be greatly reduced. Because the rectangular plunger (2a) has four sides respectively closely attached to the inside surface of the key base (3a), moving the rectangular plunger (2a) in the rectangular hole on the key base (3a) causes a great frictional force to occur. Furthermore, the outward bottom flange (21a) of the rectangular plunger (2) will be forced to strike against the inward top flange (31a) of the key base (3a) in producing a big noise as the rectangular plunger (2a) is moved back to its original position by the rubber tone (4a).